Estradiol on trigger day: Irrelevant to live birth rates of fresh cycles but positively associated with cumulative live birth rates

Abstract

ObjectiveTo assess the effects of estradiol (E2) on trigger day on cumulative live birth rates (CLBRs), and pregnancy outcomes after fresh and frozen–thawed embryo transfer (FET).MethodsThis multicenter retrospective cohort study included 42 315 patients from five reproductive centers. Six subgroups were divided according to E2 on trigger day (<1000, 1000–2000, 2000–3000, 3000–4000, 4000–5000, >5000 pg/mL). Smooth curve fitting and nonlinear mixed‐effects models were used.ResultsWhen E2 was <5500 pg/mL, the CLBR increased by 10% for every 1000 pg/mL increase in E2. When E2 was between 5500 and 13 281 pg/mL, CLBR increased by 1.8% for every 1000 pg/mL increase in E2. When E2 was >13 281 pg/mL, CLBR decreased by 3% for every 1000 pg/mL increase in E2. From group E2 < 1000 to group E2 > 5000 pg/mL, pregnancy and live birth rates in fresh cycles were not related to E2. The live birth rate after FET was higher in the E2 ≥ 5000 pg/mL group than in the E2 < 1000 pg/mL group (odds ratio [OR] 4.03, and 95% confidence interval [CI] 3.74–4.35; adjusted OR 1.20, 95% CI 1.05–1.37).ConclusionCLBR is associated with E2 on trigger day in a segmented manner. Pregnancy and live birth rates in fresh cycles were not associated with E2. The live birth rate in FET cycles was highest when E2 ≥ 5000 pg/mL.